Focus and depth of field are two parameters that largely affect the visual quality and aesthetic of image acquisition. They are especially important in motion picture films, where it may be required to pull the focus from one plane to another during a shot, for example to follow a moving object or to shift the viewers' attention to another object. Manually adjusting the focal point of the lens is difficult in this situation, especially when working with a shallow depth of field to create a film look. Professional film productions have camera assistants for this task. This does, however, not mean that focus and/or depth of field is always set correctly. Since defocusing errors cannot be fixed in post-production, they either have to be tolerated or the shoot has to be retaken.
Nevertheless lens metadata such as focal length, focus distance and focal ratio, e.g. aperture or iris value, are usually stored with the image data not only for professional but also for consumer cameras. Their value in post-production is rather informative.
In order to keep video and audio recording in sync, timecode signals are distributed among the devices on the film set. LTC (LTC: Linear or Longitudinal Timecode) is an encoding of the SMPTE (Society of Motion Picture and Television Engineers) timecode standard and can be distributed either via 5-pin LEMO connectors or HD-SDI signals (HD-SDI: High Definition Serial Digital Interface).
Light field cameras allow adjusting the focus and depth of field after shooting. This may be considered as a potential advantage to overcome the problem of defocused shots. However, it also means that the process of setting, for example, focus and depth of field is only deferred from shooting to a later point in time.
The decision may even be left up to the user. For example, a so-called “living picture” has been introduced, allowing the user to interactively set the focus distance and slightly vary the viewing angle for rendering multiple views of a same shot.
The possibility of adjusting the focus and depth of field after shooting raises the question how to define a rendering intent for every frame of light field captures and how to pass it through a motion picture production workflow.